Means for adjusting the stroke of the feed dog in sewing-machines



Jan. 13, 1959 MORO 2,868,150

MEANS FOR ADJUSTING THE STROKE OF THE FEED DOG IN SEWING-MACHINES FiledNov. :50, 1956 FIG. 2

In ventor ANTON/0 Mo/eo y W247i A torn e y United States Patent T MEANSFORADJUSTING- THE STROKE'OF THE FEED DOG IN SEWING-MACHINES AntonioMoro, Milan, ltaly assignor to S; p. A.

Fratelli Borletti, Milan, Italy "Applicafioll'Nbv embel' 30, 1956Se'nal' 'No. 625,399 Claims priority, application Italy December 20,1955 Claims. (Cl. 112-210) In sewing machines, particularly ofthedomestic kind, themechanism for adjusting the displacing amplitude orstroke of the cloth-pushing feed dog is actuated by a lever, on theangular deviation of which, either in one or in the opposite direction"withrespect to a zero position, depends the amplitude of the feed dogdisplacing either forwards or backwards and thus the stitch length ofthe seam effected in the corresponding direction.

The present invention relatesto a device for stopping said actuatinglever in any chosen position, that is to a device making it possible toestablish the feed dog displacing amplitude each time in any desiredmanner, and'keeping said amplitude equal for both the forward and thebackward displacing; said device differs from already known devices ofthe same kind due to a particular structure adapted to give it a widepossibility of varying the stop-position, assuring, at the same time, bysimple means, a speedy and safe operation.

This device is characterized in that two double-armed levers, mounted ontwo pivots respectively placed on either side of the pivot of theactuating lever of the adjusting mechanism, are so combined with twocams mounted the one over the other, with different orientation on acommon pivot, that said cams, placed between two corresponding arms ofsaid levers, held by springs adherent to the cams, impart by theirrotation in either direction a movement for opening or shuttingrespectively said levers like scissors said levers serving by means oftheir other two arms as stops for a pivot carried by the actuating leverof the adjusting mechanism.

By such a disposition the distance of the stop position from a zeroposition for the actuating lever of the adjusting mechanism deviated ineither direction is always the same, so that for each position of thedevice according to the invention the forward displacing amplitude ofthe cloth pushing feed dog is equal to the backward displacing of saidfeed dog, the stitch length thus resulting equal for both the. forwardand the backward seams as it must in fact be when a normal sewing-workis effected.

According to a further characteristic of the invention, the spring, bymeans of which the lever for determining the forward displacing of thecloth-pushing feed dog is held adherent to the corresponding drivingcam, is disposed in such a manner as to always hold said leverapproached to the stop of the actuating lever of the adjustingmechanism, the latter lever being thus always carried along by saidformer lever, in its movement.

Therefore the only driving of the stop device according to the inventionis sufficient for producing, at the same time, the driving of forwardseam of the adjusting mechanism, thus greatly simplifying the relativehandling.

In the machines of a domestic kind this is very useful, as by thesemachines only the forward seam must be generally performed, the backwardseam being required only for a few closing stitches after the forwardseam has been effected. For these closing stitches it is sufficient topush backwards the actuating lever of 'theadjusting mechanism againstthe action of the mentioned spring, which then carries forward saidlever again, as soon as the latter is set free.

The object of the present invention is illustrated by an embodiment inthe annexed drawing, in which Fig. 1 shows in front view the device in azero position, that is in the position not displacing the feed dog;

Fig. 2 is a cross section ofthe device according to lines A-B of Fig. 1;

Fig. 3 is a front view of the device shown in position for a maximumstitch length;

Fig. 4 shows a modification of the driving means for the actuating leverof the adjusting mechanism.

With reference to Figs. 1 to 3, pin 1, preferably eccentric for thephase adjusting, is fixed on bell crank lever 2 actuating the mechanismfor adjusting the dis placement of the cloth-feeding dog, that is to thelever, the position of which through a mechanism shown in More BritishPatent No. 788,081, controls the pitch and the displacing direction. ofthe feed dog transporting the cloth. It will be understood that theapparatus of the present invention replaces the feed dog operatingmechanism shown in Fig. 10 of the aforesaid British patent. Lever 2 isfixed on pivot 3 adapted to rotate in hole 4 of bearing 5 fixed to themachine frame. Externally to hearing 5, handle 6 for shifting lever 2 isfixed on pivot 3.' Pin 1 is restrained in its displacings about the axisof pivot 3 by the two arms 7 and 8 of the two levers 9 and 10,respectively pivoted at 11 and 12.

The other two arms 13 and 14 of levers 9 and 10 have the respectivesurfaces 15 and 16 always in contact with the peripheral surfaces 17 and18 respectively, of two cams 19 and 20 similar to each other but havingdifferent orientation, said cams being mounted on shaft 21 rotated fromthe outside by knob 22. These cams can be relatively displaceablebetween each other for the phase adjusting,,and can be fixed on shaft 21after the displacing.

Pin 1 of lever 2 is always held against arm 7 by spring 23, which keepsthe cam-engaging surface 15 on cam 17. Cam-engaging surface 16 of arm 14is always held in engagement with cam 18 by a spring 24.

When knob 22 is turned, cams 19 and 20 rotate, so that the distances 25and 26 from the rotation axis 21 of the contact points between thecam-engaging surfaces 15 and 16 and the surfaces of the respective cams17 and 18 vary and consequently levers 9 and 1t) rotate about therespective pivots 11 and 12. Pin 1, and thus lever 2, follows lever 9 inits displacement, while lever 8 is symmetrically displaced of the sameangle as lever 9, with respect to the central zero position (AB). In anyof these positions, the machine will sew forward with a pitchcorresponding to the position, for instance :27, taken up by pin 1, saidposition being in its turn 'determined by the angular position of cam19.

By turning handle 6 according to arrow 28 till pin 1 is stopped againstlever 8, in its new position 27, the machine will sew backward with astitch length equal to the one of the forward seam; by leaving handle 6free, all will return as before on account of spring 23, and thus forany other position of earns 19 and 20, as surfaces 17 and 18 of saidcams are, as already said, shaped so that both arms 7 and 8 of levers 9and 10 are simultaneously displaced of angular values equal between eachother with respect to the origin (AB).

In order to regulate the stitch length according to determined values,knob 22 is provided with a graduation 29 adapted to be read incorrespondence of the fixed index 39, the graduation values, forinstance, can cor- 3 respond to millimeters of the feed dog displacementfor each stitch.

Fig. 3 shows cams l9 and 20 and, respectively lever, 7 and 8 in positionof a maximum opening corresponding to the maximum stitch length: lever 2can be brought, according to arrow 28, from where pin 1 is in position31 to where it is in position 32, thus preparing the feed dog for themaximum forward and, respectively, backward stroke.

In the modified embodiment shown in Fig. 4, lever 2 carries another arm2 connected through tie rod 33 to end 34 of a lever pivoted at 35 andbeing remote from lever 2; the rotation of lever 2 is effected byactuating lever 36, all the remainder working as previously described.

It is well understood that the particulars of construction of the devicecan vary from those represented in the drawing and above described, saiddevice always remaining within the frame of the invention.

What I claim is:

1. Mechanism for controlling the setting of a feed dog control levercomprising a feed dog control lever, said lever having a pin on one armthereof, a shaft rotatably mounting said lever, second and third shaftsdisposed on opposite sides of said first shaft, a pair of displacementcontrol levers mounted on said second and third shafts and having camfollower surfaces on the lower arms thereof and engagement surfaces forsaid pin on the upper arms thereof, and adjustable cam means contactingsaid cam follower surfaces to vary the positions of said displacementcontrol levers and thereby control the range of movement of said pin andfeed dog control lever.

2. The mechanism of claim 1, said adjustable cam means comprising a pairof cam plates mounted on a common shaft, and means to turn said shaft tovary the setting of said cams.

3. The mechanism of claim 1, and spring means urging said cam followersurfaces into engagement with said cam means.

4. The mechanism of claim 1, and further including spring means urgingsaid pin into engagement with one of said engagement surfaces of one ofsaid displacement control levers.

5. The mechanism of claim 4, and further including means to rotate saidfeed dog control lever against the urging of said spring to engage saidpin with the other engagement surface of the other displacement controllever.

References Cited in the file of this patent UNITED STATES PATENTS2,679,220 Biesemeyer et a1 May 25, 1954 2,704,986 Pagni Mar. 29, 1955FOREIGN PATENTS 314,696 Great Britain July 4, 1929 360,910 Italy July 8,1938

